The association between Achilles tendon rupture and sciatica was investigated by questionnaire in 138 patients who underwent repair of an Achilles tendon rupture, and in a group of individuals nominated by the patients, matched for age, sex, and occupation. A total of 102 patients (74%) and 128 peer nominated controls (71%) replied to the questionnaire. Of the 102 respondent patients, 18 had an officebased job, 47 were involved in skilled nonmanual work, and 16 were retired. Back pain had been experienced by 63 of the patients who replied to the questionnaire, and by 91 (75%) of the individuals in the control group (difference not significant). In about 30% of both groups, the pain confined them to bed for at least two days, and resulted in absence from work. Thirteen of the patients and 16 of the controls had undergone thoracic, lumbar, or sacral radiography. One individual in each group had received surgery for back pain. However, 35 of 102 patients had experienced sciatic pain before Achilles tendon rupture. Pain of a similar nature had been experienced by only 15 individuals in the control group (12%) (p < 0.001). Using this study design, we found a highly significant association between Achilles tendon rupture and sciatica. We propose that this association could be due to impaired afferent signals from the lower leg, or to similar collagen or vascular anomalies of the vertebral disc and the Achilles tendon.